Process of oxidation oe sulfids



(3. N. LIBBY.

PROCESS OF OXlDATION OF SULFIDS.- APPLlCATlON FlLED FEB. 8, 19l6.

Patented Dec. 2, 1919.

IN V ENTOR. Gearye flelson Libby P m/AW 1 Muz /kf ATTORNEY i able to hydro-metallurgical treatment for em T ew F E GEORGE N. LI BY, or- BERKELEY, CALIFORNIA.

Application filed February '3, 1916. Serial No. 76,005.

To all whom it may concern:

Beit known that I, GEORGE NELSON L 1B BY, a citizen of the United States, and residing in the city of Berkeley,.county of Alameda,

State of California, have inyented a new 'Pr0cess of Oxidation of Sulfids.

The process relates to the art of oxidation of mineralsulfidsor sulfid ores, consisting of water-insoluble solid sulfide, and has for its object not only to render the ore amenmetal recovery, butialso-to secure the energy of oxidation as electricity.

It has been well known that mineral sulfidsmay function as electrodes but heretofore it has been considered that sulfids, especially pyrite function principally as in- .soluble electrodes, i. e. a mineral sulfid like pyrite takes its electrical charge, primarily not from its own decomposition but from the nature of the solution surrounding it, just as does the unattacked electrode platinum. This is the case in acid solutions such as have heretofore been used in hydrometallurgical treatments, but I have demonstrated that in an-alkaline solution these.

sulfids function entirely as decomposing electrodes and in no way resemble platinum or other unattackable electrodes.

In my method for the oxidation of pyrite or other conducting sulfids I employ them as an anode in an alkaline solution such as sodium hydrate or calcium hydrate. This constitutes the half cell'consisting of solid mineral sulfid in a solution of an alkali sulfid. The oxygen may be supplied by electro-decomposition of the solution with the sulfid as an anode or it may be supplied by opposing the above half cell by any half' cell having a higher electro-motive force, 2'. 6., one that is more electropositiye. However, I prefer to use one whose used oxygen may be replaced by oxygen from the air. Such a depolarizer is concentrated nitric acid surrounding an unattacked electrode,

such as metallic iron.

The battery thus constituted is of the well known Bunsen type but is novel 1n the use of a mineral sulfidzin an alkaline solution as an anode. v

The accompanying drawings illustrate cell constructions adapted for carrying out my invention, and referring thereto Figure 1 is a vertical section of a simple cell adapted for oxidation of the sulfid ore by electrolysis of the alkaline electrolyte.

Specification of Letters Patent.

PROCESS OF QXIDATION SULFIDS.

Patented Dec. 2, 1951.9.

Fig. :2 is a verticalsection of a cell comprising two half. cells in electrolytic conductive connection, one of said half cells comprising the mineral sulfid as anode, in an alkaline electrolyte, and the other half cell comprising an unattacked cathode in. a depolarizing solution.

In Fig. 1, the solid water-insoluble mineral sulfid (sulfid ore) constitutes the anode 1 in contactwith an alkaline electrolyte 2,

contained in a ressel 3. The cathode 4 may be of any suitable material. On electroly- SIS of the alkaline electrolyte by current passingtherethrough "and through the elec-,

trodes I- and l, the sulfid may be oxidized;

I prefer however to carry out the/ operation by a cell construction, for example, such as shown in Fig. 2, in which the cathode l'is of positive potential relative to the anode 1, by reason of the chemical relations or actions in the cell, so as to generate electrical energy by the oxidation of the sulfid anode, and for this purpose I prefer to use a cathode 4 of, metallic iron in a depolarizing solution, indicated at 5, preferably nitric acid, or other substance capable of reduction to a lower state of oxidation by cathode action, and of more or less complete reoxidation to its original condition by the action of atmospheric air. The cathode half cell consisting of iron in nitric acid solution is sepa rated from the anode half cell, consisting of mineral sulfid in alkaline solution, by any usual means for restraining or resisting diffusion of the constituents of the solutions while maintaining electrolytic conductive connection; for example, a. porous separator member such as indicated at 6. The electrodes 1 and 4 may be connected to wires 7 and 8 for fconducting current, either from an external source, in the case of the form shown in Fig. 1, or to an external consuming device, in the case of he form shown in Fig. 2.

pected-from the usual calulatibn by. meahs of. thg'hatsbf formation.

Having thfls 'dgs'c'ribed my invegi'tion, what I claim as ngw, -and,desir'e to scure by Let- '5 'tersfPatenfi is an de,- 'withL-an electiolytg consisting of .an

hv wswlumon oganralkali and causin cm'rventvmpass thro gh 'sz'p'id anmleand glee f l yiq so a t ox dii flfihe mineral s l d v agifan anode 'alidf'to be @xidized by electnowith n alkalinQelecttdl -a nd mafptainl .with said alkaflinb"elegztrolytqtfaichthodg in a,- dp'olarizing ,solution zapabl 'di .m'generafion by' Oxygen," and exposing jsai d polarizing solutlon to contact with oxygam; The process of oxidation of a .waterinsoluble: ini ergsl sulfid with resultant gem, erat'ibn: of ,lectriqa'l current, which consistsin'hx' ing such sulfidxas an anode. in an alkahm electrolyte, maintaining a cathodq electrolytic conductiw connegtioxi with Said" electmlyfo e, 'depolarizin g'ismd cathode by thjactiqn 9f :1 depolamzl ng' agent capable 10f; regen'eration by oxygen; and tggeneriiti'pg 'saidg depolarizing agent by the gctign'oipxygen.

5.;111? Irqcess of oxidation of' a solid 5m (1 which fconsists in .exp'qsmg 1t, is in anode "5.8 mi alkaline.e1ectr0lyte, maint'aining in eie'qtrol'ytic co'nductive connection with {gai'd-alectrolyte, acathode in' contact .50 with-( nitric acid solution and exposing said solution to contact with oxygen. GEORGE N. LIBBYF witnesseslz NATHAN 'Nnnmc,- G. L. Penn-m.

electrolytic gqn active 1 co nectiom 33* 

